The past decade of research in child temperament has been witness to a profusion of research regarding behavioral inhibition. However, several theoretical and empirical sources suggest that approach motivation may contribute to the development of externalizing problems, which may have greater societal implications than internalizing disorders associated with inhibition. The proposed study intends to focus specifically on behavioral approach and the role it plays in early psychopathology. Specifically, this inquiry will attempt to (1) demonstrate the distinct nature of approach and inhibition, using both a previously developed task and a factor analytic approach, (2) examine the stability of behavioral approach and inhibition through the first two years of life, (3) investigate connections between approach, inhibition and parent- reported behavior problems, and (4) relate cardiac responsivity to auditory stimuli and cardiac vagal tone, a measure of parasympathetic influence, to approach, inhibition, and behavior problems. Comparisons will be made between approach and inhibition, measured via a toy-reaching paradigm, at 6 and 12 months and a battery of tasks based on subdimensions of the adult personality construct of sensation seeking administered at 24 and 25 months. In addition, parents will complete the Child Behavior Checklist for Ages 2-3. It is predicted that high levels of behavioral approach will be associated with externalizing symptoms and elevated parasympathetic tone, whereas high levels of behavioral inhibition will be associated with internalizing problems and low parasympathetic input.